1. Field of the Invention
The present invention relates to a production method of a decorative film used for decoration of office automation equipment and home appliances, or molded components such as automotive interior materials, e.g., center panels, console boxes, switch bases, and so on.
2. Related Background of the Invention
Examples of the known methods of producing the molded components such as the automotive interior materials decorated with the decorative film include methods such as hydrographic transcription, in-mold molding, and insertion molding. Among these, the production method by insertion molding is particularly generally employed in recent years.
In this insertion molding, a thermoplastic resin such as vinyl chloride resin, acrylonitrile-butadiene-styrene resin (hereinafter referred to as “ABS resin”), or olefin resin is molded by injection molding on a back surface of a decorative film (a surface on the base film side) formed in a predetermined 3D shape by a method such as vacuum molding, pressure forming, vacuum pressure forming, or press molding, thereby obtaining a molded product integrated with the decorative film.
The mainstream of the conventional production methods of decorative film was a production method including a step of “coating”: a pattern layer (design layer) is printed onto a base film of vinyl chloride resin, and a polyurethane resin is applied onto the pattern layer to form a transparent resin layer (clear layer).
Besides the above methods, a special production method of decorative film is a method of performing continuous thermal pressing to laminate a transparent, vinyl chloride resin film or acrylic resin film on a pattern layer provided on one surface of a base film of vinyl chloride resin to form a transparent resin layer (clear layer).
A known decorative film is one having a configuration in which a base film of a resin composition consisting of a mixture of a vinyl chloride resin and an ABS resin of 30 or more % by weight thereof is used as an adhesive layer and in which a pattern layer of a vinyl chloride resin and a transparent resin layer of a thermoplastic resin such as acrylic resin, vinyl chloride resin, polycarbonate resin, or fluorocarbon resin are stacked in this order on one surface of the adhesive layer (Japanese Utility Model No. 3015173).
Incidentally, in order to cope with environmental issues, recycling issues, etc. in recent years, the vinyl chloride resin used heretofore has been and is being replaced by other resins such as the ABS resin, olefin resin, and so on, as the resin for injection molding for forming the molded components to be decorated with the decorative film. For example, where the ABS resin is used instead of the vinyl chloride resin, it is also necessary to use the ABS resin for the base film of the decorative film.
However, many resins including the ABS resin, used as substitutes for the vinyl chloride resin, are inferior in solvent resistance and, therefore, it is very difficult to directly print the pattern layer on the surface of such resins.
Then, for example, a method sometimes employed is to print the pattern layer on the transparent resin layer of acrylic resin, contrary to the case of the vinyl chloride resin, and to laminate the base film of ABS resin thereon (Japanese Patent Application Laid-Open No. 11-91041).
Another method is to prepare a laminate in which one surface of a carrier film with excellent solvent resistance is coated with polyurethane resin or the like to form a transparent resin layer and in which the pattern layer is printed thereafter on the transparent resin layer, and to thermally transfer the pattern layer and the transparent resin layer from the laminate onto a base film of ABS resin.